Latitude and Longitude Rulers
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STEM Earth Central 2007
Latitude and Longitude Rulers
Objectives:
 To construct paper rulers to determine the Latitude and Longitude of any location
on a United States Geologic Survey (USGS) topographic map.
 To compare data collected using these rulers with data collected using a GPS
personal navigator.
A. Find Longitude Lines:
Question 1: Longitude numbers are located at all four corners of a USGS map. What
Longitude line runs north and south along the eastern edge of the map? Use symbols to
record the Longitude. For example: 71° 30’ 30” W.
Question 2: What Longitude line runs south and north along the western edge of the
map? Use symbols to record the Longitude.
Question 3: How many minutes of Longitude are there between the eastern and western
edges of the map?
B. Make a ruler that indicates degrees and minutes of Longitude.
Cut a strip of paper to place along the southern edge of the map. The paper strip
should extend beyond both the eastern and western edges of the map.
Place the paper strip along the southern edge of the map so that you can mark the
Longitudes at the eastern and western edges of the map.
Measure and record the number of centimeters between the two pencil marks on the
strip of paper.
Calculate and record the number of centimeters in each minute of Longitude
Longitudes increase as you travel to the west in the Western Hemisphere. Begin to
construct your Longitude scale at the eastern edge of your Longitude ruler as shown in
Figure 1 at the bottom of the page. Place and label a mark for each minute of Longitude.
This ruler can be used to estimate Longitude to the nearest minute.
Latitude and Longitude Rulers
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GPS devices can indicate Longitude in degrees, minutes, and seconds. If that is the
case then the directions in Section C apply. GPS devices can also divide minutes of
Longitude using decimals. If that is the case, then the directions in Section D apply.
C. Make a “minute ruler” to estimate Longitude to the nearest second.
Cut a strip of paper slightly wider that a minute of Longitude. Divide the number of
centimeters in one minute of Longitude into 6 equal sections.
Question 4A: How many centimeters represent 10 second of Longitude?
Use a pencil to divide the minute of Longitude into six 10 second sections as shown in
below. Label each mark. Start at the eastern end of a minute of Longitude. This shorter
ruler can be used with any one minute section of the longer Longitude ruler. The shorter
ruler can also be used as a template to subdivide each minute of the Longitude ruler.
D. Make a “minute ruler” to measure minutes of Longitude in decimal form.
Cut a strip of paper that is slightly wider that a minute of Longitude. Divide the
number of centimeters in one minute of Longitude into 10 equal sections. Each section
represents a tenth of a minute of Longitude.
Question 4A: How many centimeters are in each tenth of a minute of Longitude?
Use a pencil to divide the minute of Longitude into tenths is shown in Figure 2B below.
Label each mark. Start at the eastern end of a minute of Longitude. This shorter ruler can
be used with any one minute section of the longer Longitude ruler. The shorter ruler can
also be used as a template to subdivide each minute of the Longitude ruler.
Latitude and Longitude Rulers
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Determine a Longitude at any location on the map.
Put your Longitude ruler parallel to the southern edge of the map. Slide the ruler to
the north until you reach a location at the front entrance of Hasbrouck Lab on the map.
Be sure to keep the ruler parallel to the southern and northern edges of the map.
Question 5: What is the Longitude at the front entrance of Hasbrouck Lab? For
example: 71° 5' 35" W or 71° 5.58’ W
Question 6: How does the value measured with ruler compare with the GPS value?
Question 7: What are possible sources of error when constructing paper Longitude rulers
using a USGS map?
Question 8: How many significant figures are in your Longitude value?
E. Find Latitude Lines:
Question 9: Latitude numbers are located at each of the four corners of the USGS map.
What Latitude line runs east and west along the southern edge of the map?
Use symbols to record the Latitude. (for example: 41° 20’ 30” N)
Question 10: What Latitude line runs east and west along the northern edge?
of the map? Record the Latitude using symbols
Question 11: How many minutes of Latitude are between the southern
and northern edges of the map?
F. Make a Latitude Ruler.
Tear a paper strip to place along the eastern edge of the map. The strip
should extend beyond both the southern and northern edges of the map.
Mark the paper strip at the southern and northern edges of the map and
measure the number of centimeters between the marks.
Divide the distance between the pencil marks by the number of minutes
of Latitude between the southern and northern edges of the map. Record
the number of centimeters that represents a minute of Latitude.
Place a mark for each minute of Latitude. Start at the northern end of
the Latitude ruler so that the half minute section is at the southern edge
of the ruler. Notice the half minute at the southern end of the ruler.
Indicate the Latitude at each end of the ruler as shown in Figure 3 in the
margin on the right. Label each minute mark.
Latitude and Longitude Rulers
Important Notes: A Latitude ruler indicates increasing Latitudes from South to
North on a map. The Latitude ruler for the Williamsburg USGS quadrangle map has a half
minute section at the southern end of the ruler. Some maps have a half minute section at
the northern end of the map.
GPS devices can indicate Latitude in degrees, minutes, and seconds. If that is the case
then the directions in Section G apply. GPS devices can also divide minutes of Latitude
using decimal. If that is the case, then the directions in Section H apply.
G. Make a “minute ruler” that to estimate Latitude to the nearest
second.
Cut a strip of paper that is slightly wider that a minute of Latitude.
Divide the number of centimeters in one minute of Latitude into 6 equal
sections. Each section represents 10 seconds of Latitude.
Question 12A: How many centimeters are in each 10 second section of a
minute of Latitude?
Use a pencil to divide the minute of Latitude into six 10 second sections
as shown on the right. Label each mark. Start at the southern end of a
minute of Latitude. This shorter ruler can be used with any one minute
section of the longer Latitude ruler. The shorter ruler can also be used
as a template to subdivide each minute of the Latitude ruler.
H. Make a “minute ruler” to measure minutes of Latitude in
decimal form.
Cut a strip of paper that is slightly wider that a minute of Latitude.
Divide the number of centimeters in one minute of Latitude into 10
equal sections. Each section represents a tenth of a minute of Latitude.
Question 12B: How many centimeters are in each tenth of a minute of
Latitude?
Divide the minute of Latitude into tenths as shown in Figure 4B. Label
each mark. Start at the southern end of a minute of Latitude.
This shorter ruler can be used with any one minute section of the longer
Latitude ruler. This shorter ruler can also be used as a template to
subdivide each minute of the Latitude ruler.
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Latitude and Longitude Rulers
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Determine Latitude at a location on the map.
Place your Latitude scale parallel to the eastern edge of the map. Slide your scale to
the west across the map until you have reached a location on the map. Be sure to keep
your scale parallel to the eastern and western edges of the map.
Question 13: What is the Latitude at the front entrance of Hasbrouck Laboratory? For
example: 41° 5' 35" N or 41° 5.6’ N.
Question 14: How does that value compare with the value obtained using a GPS device?
I. Compare Minutes of Latitude and longitude.
Distance scales are located at the bottom of the map and indicate map distances in
miles and kilometers.
Question 15: What are the following map measurements?
 The number of kilometers and miles in one minute of Latitude
 The number of kilometers and miles in one minute of Longitude
Question 16: Why would a minute of Longitude equal less distance than a minute of
Latitude as you move north or south from the Equator?
Question 17: Why would a minute of Latitude always be equal to the same distance at any
Latitude?
A minute of Latitude is referred to as a Nautical Mile. A ship or airplane that is
traveling at a speed of 50 nautical miles per hour is traveling at a speed of 50 knots.
Question 18: What would be the coordinates at the corners of 7.5 x 15 minute USGS
maps that are directly to the
 East of the Williamsburg map (the Shutesbury quadrangle map)?
 North of the Williamsburg map (the Greenfield quadrangle map)?
 West of the Williamsburg map (the Goshen quadrangle map)?
Note: A 15 x 7.5 quadrangle map is not available for the Easthampton area that is directly
South of the Williamsburg map. A 7.5 x 7.5 Easthampton map is available and can be
combined with a 7.5 x 7.5 Westhampton map to create a map similar to the Williamsburg
map.
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Latitude and Longitude Rulers
J. The USGS/GPS connection:
Latitudes and Longitudes of locations obtained from a map can be entered as coordinates of a
“Waypoint” in a GPS. Examples of Earth Central “Waypoints” include:

The swimming beach at Puffer’s Pond (Factory Hollow Pond on the Williamsburg USGS map).
42° 24’ 52” N or 42° 24.866’ N

The Mill River location where we will measure stream flow. Mill River is located downstream
from the dam that was built to create Puffer’s Ponds in order to harvest ice.
42° 24 42” N or 42° 24.7’ N
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72° 32’ 12” W or 72° 32.20’ W
The Tuesday Evening Barbecue at 41 Hitching Post Road
42° 24’ 37” N or 42° 24.610’ N
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72° 31’ 40” W or 72° 31.67 W
The UMass Sunwheel that marks events such a sunrise or sunset on a solstice or an equinox.
42° 22’ 28” N or 42° 22.466’ N
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72° 31’ 04” W or 72° 32.066’ W
72° 30’ 38” W or 72° 30.633’ W
The field trip at Mt. Toby will begin at:
42° 27’ 47” N or 42° 27.783’ N
72° 33’ 55” W or 72° 33.917’ W
To enter coordinates obtained with paper Latitude and Longitude rulers into a
Garmin GPS personal navigator you need to:
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Press and hold down the ENTER button until the Mark Waypoint Page appears.
A number will appear in the Name Data Field (e.g., 004) as a temporary name.
Use the ROCKER to move the highlight to the Name Data Field. Press ENTER
A highlight will appear on the first number of the temporary name.
Use the ROCKER to move up through numbers to letters for the first letter of a name for
the Waypoint.
Use the ROCKER to highlight the next number in the temporary name.
Use the ROCKER to move up through numbers to get to letters for the second letter of a
name you have chosen for the Waypoint.
Continue to create a name for the Waypoint.
Press ENTER when you have finished creating a name for the Waypoint.
Use the ROCKER to move the highlight to the Location field. Press ENTER.
Use the ROCKER to highlight the first number in the Latitude that needs to be changed.
Use the ROCKER to increase or decrease that number.
Use the ROCKER to move to the right to highlight and change the next number that needs
to be changed. Finish changing numbers in the Latitude.
Use the ROCKER to keep moving to the right so that it goes down to Longitude numbers.
Make any necessary changes in the Longitude numbers. Press ENTER when finished.
Use the ROCKER to highlight OK. Press ENTER. The Waypoint is now saved.